Almost every day of the week, police officers are called to the scene of a traffic accident to provide assistance. More often than not, these officers report to a street intersection rather than an address along a residential street. But how many times does a police officer report to the same intersection? Moreover, are there trends occurring for high traffic volume intersections? These were the sorts of questions the Traffic Safety Committee of the City of Park Ridge aimed to study. In addition, the committee wanted to analyze how many accidents per month were happening at each intersection. Furthermore, they needed and easy method for displaying these results to the whole committee.

With these ideas in mind, the Traffic Safety Committee requested the services of the Geographic Information System (GIS) Department. By using the tools located within the GIS, each intersection accident that was recorded by the Police Department could easily geocoded to a geographical location. Geocoding is an operation that searches a street or address data file and locates the coordinate where an address falls on a particular street, in this case, the tool located the intersection where the accident occurred.

Once the intersections are located, they are placed on a map in order to analyze where the most accidents occur. The GIS Department recommended representing each the number of accidents at each intersection as a graduated symbol. This made it easier to discern which intersections had the more accidents than other intersections (for example, large circles for a high accident count and small circles for a low accident count). By using this methodology, the final map product was much easier to read and allowed the Traffic Safety Committee to easily target which intersections required the more attention for traffic safety studies.

Since the inception of this project, the analysis has been performed every three months and all maps are immediately submitted to the Traffic Safety Committee. Overall, it is easy to see how by taking data from a simple recording project and using Geographic Information System tools to analyze the data, the city was able to continue providing their residents with the service of traffic safety.